1,721,294 research outputs found
Nuova prospettiva di studio della qualità degli aceti: analisi della distribuzione delle dimensioni molecolari
No full textIn questo studio è stata utilizzata una tecnica di Gel-Permeation Chromatography (GPC), solitamente impiegata nello studio dei materiali polimerici, per lo studio delle caratteristiche di distribuzione di alcune proprietà legate alla composizione e alla struttura molecolare di alcuni aceti di fermentazione. I risultati supportano la tesi che la qualità di tali aceti sia strettamente legata alla presenza di sostanze di natura polimerica derivanti dalle materie prime utilizzate per la loro produzione o prodotte ex-novo durante i processi di produzione e invecchiamento. Tali prodotti alimentari possono essere convenientemente definiti come “miscele acide di co-polimeri, bruni e incolori, con dimensione molecolare relativa compresa tra 0,2 e 2.000 kDa ed oltre, altamente polidispersi rispetto alla composizione e struttura molecolare e la cui ampiezza e modalità di distribuzione sono funzione delle materie prime utilizzate per la loro produzione e del tempo d’invecchiamento”. Come già noto da lungo tempo per altri materiali polidispersi, è ragionevole aspettarsi che anche la qualità degli aceti di fermentazione sia determinata da proprietà, chimiche, fisiche e sensoriali la cui entità non può essere quantificata con un singolo valore ma piuttosto come una distribuzione discreta di livelli. Le ricadute di tale risultato sono di enorme interesse sia dal punto di vista scientifico che produttivo in quanto apre nuovi orizzonti nella comprensione su base molecolare delle molteplici proprietà funzionali del prodotto finito
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
LA RIPROGRAMMAZIONE DI ASTROCITI UMANI IN CELLULE NEURO-STAMINALI E NEURONI COME POSSIBILE STRUMENTO TERAPEUTICO PER LE PATOLOGIE NEUROLOGICHE
Full text linkGenerating neural stem cells and neurons from reprogrammed human astrocytes
is a potential strategy for repair in neurological diseases.
It has been recently showed that astrocytes from murine cerebral cortex can be
differentiated into neurons by the forced expression of a single transcription factor
(Heinrich et al., 2010). While these studies have evaluated astrocyte conversion in
the murine context, a similar possibility has yet to be demonstrated in human cells.
An essential element for developing such applications with therapeutic value is a
thorough comprehension of the mechanisms that regulate reprogramming of adult
cells into induced pluripotent stem cells (iPSCs) (Hanna et al., 2010) or directly into
another committed lineage, such as fibroblasts converted into neurons and also
specific neuronal subpopulations like dopaminergic neurons (Pang et al., 2011,
Caiazzo et al., 2011).
Here we demonstrate the possibility to obtain progenitors and mature cells of the
neural fate directly from human cortical astrocytes with a dedifferentiation into
neural stem/progenitor phenotype.
Even if for the purpose of autologous cell transplantation in neurological disorders,
fibroblasts from patients resemble a much more suitable source of neurons than
astrocytes from patients, nevertheless, shading light in the mechanisms that make
possible to reprogram astrocytes into NSCs is useful for the final goal of using
these cells as endogenous cell source for in situ neural repair in the CNS without
any invasive cell graft. Human astrocytes can be reprogrammed into iPSCs, with
similar efficiencies to other cells, using the viral expression of four reprogramming
factors (Oct4, Sox2, Klf4, and cMyc) (Riuz et al., 2008). Remarkably,
overexpression of a single factor like OCT4 in adult cells can induce full
reprogramming, as when it is expressed in NSCs (human and mouse) (Kim et al.,
2009 a, b) or promote the formation of another phenotype, such as the generation
of blood cells with its expression in human fibroblasts (Szabo et al., 2010). These
data suggest that the effect of these stem reprogramming factors changes in
relationship to the lineage and the differentiation stage of the cells expressing
them. In the current work, using the individual expression of OCT4, SOX2, or
NANOG, we demonstrated and characterized the direct neural fate conversion of
human astrocytes into multipotent neural progenitors, in vitro and in vivo. These
cells were generated in a manner that is independent of iPSC production.
Individual ectopic expression of the reprogramming factors OCT4 or SOX2 or
NANOG into astrocytes, together with specific cytokine/culture conditions,
activated the neural stem gene program and induced the generation of cells
expressing neural stem/precursors markers. This change of lineage commitment
was obtained also in pure CD44+ mature astrocytes and did not require passing
through a pluripotent state. These unique astrocytes-derived neural stem cells
gave rise to neurons, astrocytes and oligodendrocytes, and showed in vivo
engraftment properties. ASCL1 expression further promotes the acquisition of a
neuronal phenotype in vitro and in vivo. ASCL1 expression further promotes the
acquisition of a neuronal phenotype in vitro and in vivo (Kim et al., 2009). To
develop a broader understanding of astrocytes reprogramming we performed a methylation analysis demonstrating that epigenetic modifications underlie this
process.
These observations indicated that the sites of epigenetic and gene expression
changes during reprogramming of astrocytes to NSCs are tightly linked to genes
that are functionally important for pluripotency. These data demonstrate restoration
of multipotency from human astrocytes, and point out a possible application of
cellular reprogramming to endogenous CNS cells for repair of neurological
disorders
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
